The present invention concerns a procedure and a device for removing from water, when water is being evaporated or distilled, volatile substances such as hydrocarbons, halogenated hydrocarbons, alkanes, alkenes, methanes, chlorophenols, and benzene derivatives.
Presence of halogenated hydrocarbons in the environment and in man, which has recently received increasing attention, may be noted as an example. The most common procedure applied in purification is chlorination of water, in connection with which halogenated hydrocarbons originating from chlorine are formed in the water and remain therein. In the environment, halogenated hydrocarbons occur, e.g., in chlorine-disinfected drinking water, and such halogenated hydrocarbons have also been found in human serum and urine. Table 1 is a listing of the occurrence of certain volatile impurities. In the case of volatile hydrocarbons, trihalomethanes may be noted among these major groups listed in Table 1, with chloroform being the most notable among these trihalomethanes. Halogenated hydrocarbons are toxic, carcinogenic, mutagenic and teratogenic to humans. The halogenated hydrocarbons possess lipophilic character and therefore accumulate in tissues, even when present at minimal concentrations in the environment.
It has now been demonstrated that this matter is timely and topical, for instance in the case of patients to whom prolonged fluid therapy has been prescribed, and to whom such accumulations of toxic substances may become fatal.
The compounds in questions are low-molecular and hard to evaporate when dissolved. Experience has demonstrated that these compounds cannot be completely removed from water by any conventional procedures such as activated carbon filtration or even inverted osmosis. Referring to volatile hydrocarbons, this is particularly true concerning chloroform (CHCl.sub.3), which is most common among these volatile hydrocarbons. These compounds also fail to be removed in conventional distilling processes, in which these compounds travel along with the vapor to the distillate, instead.
According to patent DE-859879, excess chlorine is removed by conducting air and ultrasonic vibrations into the water to be purified, whereby chlorine departs along with the air bubbles.
It is common knowledge that the toxic substances noted above can be removed from water by using air, whereby the concentration of halogenated hydrocarbons is also reduced. However, a drawback of this method is that it requires an additive to the apparatus which is superfluous in view of the distilling process to be conducted, namely compressed air. Furthermore the required air quantity with which purification is effected is quite large, while the standard of purity which is required to be met is difficult to achieve.